This indicates an attack attempt to exploit a Denial of Service vulnerability in ISC BIND.
The vulnerability is caused by an error when handing requests modified by the Response Policy Zone (RPZ) module. It allows a remote attacker to cause a denial of service condition the vulnerable server.
ISC BIND 9.8.0 to 9.8.4-P1
ISC BIND 9.9.0 to 9.9.2-P1
Denial of Service: Remote attackers can crash vulnerable systems.
Currently we are unaware of any vendor supplied patch of this issue.